The importance of system development
System development can be interpreted to dispose a new system to replace the preceding system as a whole or restore the existing system. The preceding system must to be repaired because:
v Mark sense about problem that arises at preceding system. The problems such as:
a. Mistake
Mistake in preceding system causes system that can’t operate according to expected. A mistake can be as a fault that didn’t intentional so cause truths of reducing data are secured.
b. Organizational growth
Organization growth caused must be disposed the new system. The organization growth such as information requirement that little by little extends, data processing volume increased, changing accounting principle a new one.
v Get the opportunities
Information Technology expanding very quickly, then organizational start to feel that this TI require to be used ready to increase information. in emulation of market, speed of time efficiency or information very determining success or failure of plan which have been made arrangements for to reach for existing opportunities.
v Directives
The display of a new system can be done cause of being of instructions from the leader or from the outside of organization.
Purpose of developing an information system
- solve some problems
- reach for opportunity
- gratifying the given instruction
The organization’s expectations after implementing an information system
The Parameter that must be improves to the new system. The improvement related to PIECES, such as:
- Performance, the improvement of performance in a new system make the system will be effective.
- Information, the improvement of information quality which presented.
- Economy, the improvement of benefits and advantages or decreasing cost.
- Control, the improvement of control to detection and repairing some faults and insincerity which possible happened.
- Efficiency, the improvement of operating efficiency. Efficiency related with how to use resource without doing extravagance.
- Services, the improvement of services given by system.
The principles of developing an information system
- System for the management of
- System big investment
- Minimizing missing cost opportunity
- Best investigation have to be valuable : analysis cost-benefit & analysis cost-effectiveness
- System need educated people
- not education have to be formal
- System Development cycle life
- System development not have to massage
- Don’t fear to cancel project
- System documentation
Systems Development Life Cycle
The Systems Development Life Cycle (SDLC) is a abstract model used in project management that describe the stages concerned in the information system development project from an initial probability study through maintenance of the completed application. Various SDLC methodologies have been developed to guide the processes concerned including the waterfall model (the original SDLC method), rapid application development (RAD), joint application development (JAD), the fountain model and the spiral model. Generally, several models are united into some sort of hybrid methodology. Documentation is critical in spite of the type of model chosen or devised for any application, and usually done in parallel with the development process. Some methods work better for definite types of projects, but in the final analysis, the most important factor for the success may be how directly particular plan was followed.
1. The image below is the classic Waterfall model methodology, which is the first SDLC method and it describes the various phases involved in development.
Briefly on different Phases:
Requirement Analysis and Design
Analysis gathers the requirements for the system. This stage includes a detailed study of the business needs of the organization. Options for changing the business process may be considered. Design focuses on high level design like, what programs are needed and how are they going to interact, low-level design (how the individual programs are going to work), interface design (what are the interfaces going to look like) and data design (what data will be required). During these phases, the software’s overall structure is defined. Analysis and Design are very crucial in the whole development cycle. Any glitch in the design phase could be very expensive to solve in the later stage of the software development. Much care is taken during this phase. The logical system of the product is developed in this phase.
Implementation
In this phase the designs are translated into code. Computer programs are written using a conventional programming language or an application generator. Programming tools like Compilers, Interpreters and Debuggers are used to generate the code. Different high level programming languages like C, C++, Pascal and Java are used for coding. With respect to the type of application, the right programming language is chosen.
Testing
In this phase the system is tested. Normally programs are written as a series of individual modules, these subjects to separate and detailed test. The system is then tested as a whole. The separate modules are brought together and tested as a complete system. The system is tested to ensure that interfaces between modules work (integration testing), the system works on the intended platform and with the expected volume of data (volume testing) and that the system does what the user requires (acceptance/beta testing).
Maintenance
Inevitably the system will need maintenance. Software will definitely undergo change once it is delivered to the customer. There are many reasons for the change. Change could happen because of some unexpected input values into the system. In addition, the changes in the system could directly affect the software operations. The software should be developed to accommodate changes that could happen during the post implementation period.
2. In software development, iterative is used to describe a heuristic planning and development process where an application is developed in small sections called iterations. Every iteration is reviewed and critiqued by the software team and potential end-users, insights gained from the critique of iteration are used to determine the next step in development. Data models, which are mostly used to map out iterations, keep track of what has been tried, approved, or discarded, and eventually serve as a kind of blueprint for the final product.
The challenge in iterative development is to make sure all the iterations are compatible. As every new iteration is approved, developers may employ a technique known as backwards engineering, which is a systematic review and check procedure to make sure each new iteration is compatible with preceding ones. The advantage of using iterative development is that the end-user is involved in the development process. Instead of waiting until the application is a final product, when it may not be possible to make changes easily, problems are identified and solved at each stage of development. Iterative development is sometimes called circular or evolutionary development.
3. The spiral model, also known as the spiral lifecycle model, is a systems development lifecycle (SDLC) model used in information technology (IT). This model of development combines the features of the prototyping model and the waterfall model. The spiral model is favored for large, expensive, and complicated projects.
Steps of the spiral model:
- The new system requirements are definite in as much detail as possible. This generally involves interviewing a number of users representing all the external or internal users and other aspects of the existing system.
- A prelude design is formed for the new system.
- A first prototype of the new system is constructed from the preliminary design. This is usually a scaled-down system, and represents an approximation of the characteristics of the final product.
- A second prototype is evolved by a fourfold procedure: (1) evaluating the first prototype in terms of its strengths, weaknesses, and risks; (2) defining the requirements of the second prototype; (3) planning and designing the second prototype; (4) constructing and testing the second prototype.
- At the customer’s option, the entire project can be aborted if the risk is deemed too great. Risk factors might involve development cost overruns, operating-cost miscalculation, or any other factor that could, in the customer’s judgment, result in a less-than-satisfactory final product.
- The existing prototype is evaluated in the same manner as was the preceding prototype, and, if necessary, another prototype is developed from it according to the fourfold procedure outlined above.
- The preceding steps are iterated until the customer is satisfied that the refined prototype represents the final product desired.
- The final system is constructed, based on the refined prototype.
- The final system is thoroughly evaluated and tested. Routine maintenance is carried out on a continuing basis to prevent large-scale failures and to minimize downtime.
Approaches of developing a system
v Classic approach vs. approach of structure
Classic approach is approach inside of developing a system that follow stages at system life cycle without supplied with tools and techniques.
Troubleshoots which can arise from this approach, such as:
- Difficult development.
Classic approach less give tools and techniques insides develop system and finally software development process becoming not directional and difficult to be done by programmer.
- Treatment cost or system maintenance will be more expensive.
The expensive treatment cost at classic approach caused system documentation that developed less complete and less structured.
- Possibility of big error.
This approach doesn’t prepare to manner systems analysis to do system testing, so that system errors possibility will be bigger.
- System achievement less well guaranteed.
Because classic approach less involve system user in system development, so system user needs are less matching with the one which desirable and as finally system that applied less success.
- Applying internal issue.
User will be startled and unaccustomed with new system suddenly introduced.
v Approach of structure
- Consumer involve from early to determine requirement of system
- Using tools-tools like data of flow diagram
v Piecemeal approach vs. system approach
- Piecemeal approach is system approach development that emphasized at one particular activity or certain application. This approach don’t heed overall target.
- System approach pays information system as integration unitary to each activity or the application. This approach also emphasized in overall goal achievement from organization, not only in that information target.
v Approach of bottom-up vs. approach of up-down
- Bottom-Up Approach had begun from level under organization, that is begun from needs formulation to handle transaction and climb level on with formulate information need based on transaction. This approach also is feature classic approaches. Bottom-up approach is used in systems analysis stage is called also with data analysis, because that be pressure data that be cultivated before hand, information that be produced to follow to follow the data.
- Top-Down Approach on the contrary begun from level on organization, that is begun with define target and organization policy. Step furthermore from this approach information need analysis. After information is determined, so process goes to transaction processing, that is determination output, input, data base, operating procedure and control. This approach be feature from structured approach. Top-down approach when used in systems analysis stage called also with term decision analysis, because that be pressure information that wanted for decision making by management beforehand, then data necessary cultivated to defined to follow information that wanted.
v comprehensive system vs. modular approach
Total-system approach to be approach develops system together according to comprehensive. This approach less synchronized for complex system, because will be difficult be developed. This approach be feature classic approaches.
Modular Approach tries to divide complex system to simple some part, so that system easier will be understood and developed. Furthermore consequence system can be developed of time that planned, easy understood by system user and easy to maintain. This approach be feature structured approaches.
v great-loop approach vs. evolutionary approach
Great-loop approach applies change comprehensive according to together use sophisticated technology. This change contains many risks, because computer technology so great-loop. This approach also too expensive, because need investment at the same moment for all technology that used and difficult to developed because too complex. Evolutionary approach apply sophisticated technology just for applications that need that moment and then be developed for periods next based on technology development. This approach causes investment not too expensive and can follow fast technology development.
The meaning of methodology, method and algorithm
Method those are utilized in scholarship
Someway systematic to work something
Medley procedural to solves a problems
The classifications of development methodology
There are three classifications of developing a system, such as:
Functional decomposition is emphasizing system resolving becomes subsystem. Examples of this classification are HIPO, Stepwise refinement, iterative stepwise refinement and information hiding.
Data-oriented is emphasizing on processed data characteristic.
- Flow oriented data: types appropriate modules data elements
- Structure oriented data: input structure and output
- Prescriptive
Usually been provided by software maker factory
Tools for developing a system
- Get graph form: HIPO, SADT, Jackson’s diagrams, etc.
- Tool that utilizes to design:
o Activity charting: figuring activity, example: chart’s substituting, flowchart, etc.
o Layout charting: figuring layout
o Personal relationship charting: figuring person relationship, example: organization chart, working distribution chart
Techniques used in developing a system
- Project management techniques à to scheduling project, example: CPM and PERT
- Tech finds fact à to gather and determines data / fact
o Interview
o Observation
- analysis’s tech cost / benefit à cost benefit and cost effectiveness analysis
- Going tech shuts close
- Inspection tech
The differences of being a system analyst and a programmer and the knowledge a system analyst should posses
System analyst studying problems and determine system user requirements to identify resolving.
Programmer writing program code bases engineering that made by analyst
- System analyst on call bridges distinctive happening science among system user and Data processing technology, computer and mathematics
- Science carries on business in common
- Quantitative method: regression, programming linear, etc. it
- Trouble-shooting membership
- Communication membership among person
- Membership builds relationship among person programmer
